A dual role for cell plate‐associated PI4Kβ in endocytosis and phragmoplast dynamics during plant somatic cytokinesis

First author: Feng Lin; Affiliations: Martin‐Luther‐University Halle‐Wittenberg (马丁路德·哈勒维腾贝格大学): Halle, Germany

Corresponding author: Ingo Heilmann

Plant cytokinesis involves membrane trafficking and cytoskeletal rearrangements. Here, we report that the phosphoinositide kinases PI4Kβ1 and PI4Kβ2 integrate these processes in Arabidopsis thaliana (Arabidopsis) roots. Cytokinetic defects of an Arabidopsis pi4kβ1 pi4kβ2 double mutant are accompanied by defects in membrane trafficking. Specifically, we show that trafficking of the proteins KNOLLE and PIN2 at the cell plate, clathrin recruitment, and endocytosis is impaired in pi4kβ1 pi4kβ2 double mutants, accompanied by unfused vesicles at the nascent cell plate and around cell wall stubs. Interestingly, pi4kβ1 pi4kβ2 plants also display ectopic overstabilization of phragmoplast microtubules, which guide membrane trafficking at the cell plate. The overstabilization of phragmoplasts in the double mutant coincides with mislocalization of the microtubule‐associated protein 65‐3 (MAP65‐3), which cross‐links microtubules and is a downstream target for inhibition by the MAP kinase MPK4. Based on similar cytokinetic defects of the pi4kβ1 pi4kβ2 and mpk4‐2 mutants and genetic and physical interaction of PI4Kβ1 and MPK4, we propose that PI4Kβ and MPK4 influence localization and activity of MAP65‐3, respectively, acting synergistically to control phragmoplast dynamics.

植物胞质分裂涉及到膜的运输和细胞骨架重排。本文报道了磷酸肌醇激酶PI4Kβ1和PI4Kβ2在拟南芥根中介导这些进程。拟南芥pi4kβ1 pi4kβ2双突变体中细胞动力学缺陷同时会伴随着膜运输的缺陷。作者的研究显示拟南芥pi4kβ1 pi4kβ2双突变体中KNOLLE和PIN2蛋白在细胞板上的运输、网格蛋白招募和内吞作用均受损，同时还会伴随着新生细胞板和细胞壁残端周边的未融合小泡。有趣的是，pi4kβ1 pi4kβ2植株同样表现出成膜体微管的异位过稳定，而成膜体微管能够介导细胞板上的膜运输。双突植株中成膜体的过稳定与微管相关蛋白MAP65‐3的错定位结果一致，MAP65‐3交叉连接微管，并且是MAP激酶MPK4介导的抑制的下游靶标。基于pi4kβ1 pi4kβ2突变体和mpk4‐2突变体之间类似的细胞动力学缺陷以及PI4Kβ1和MPK4之间的遗传和物理互作，作者假设PI4Kβ和MPK4分别会影响MAP65‐3的定位和活性，进而二者协同控制成膜体的动态。

通讯：Ingo Heilmann (https://www.biochemtech.uni-halle.de/zellulaere_biochemie/2351734_2357974/cv_heilmann/?lang=en)

个人简介：1991-1996年，柏林自由大学，生物学学士；1997-2000年，柏林自由大学和北卡罗来纳州立大学，博士；2000-2001年，北卡罗来纳州立大学，博士后；2001-2004年，布鲁克海文国家实验室，博士后。

研究方向：植物磷酸肌醇PI相关研究。

doi: 10.15252/embj.2018100303

Journal: The EMBO Journal

Published online: January 07, 2019